Multi-component nozzle system

ABSTRACT

A pick-and-place machine and method includes use of a passive component feeder cartridge including a feeder gear. Rotation of the feeder gear causes a component-bearing tape to be fed through the feeder cartridge. A pickup head includes a vacuum nozzle to pick up the components from the tape and a rack gear to engage and drive the feeder gear of the feeder cartridge via translational motion of the pickup head when operatively disposed with respect to a selected feeder cartridge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following concurrently filed andcommonly owned applications:

1. Ser. No. 13/837,327, filed Mar. 15, 2013, entitled: Passive FeederCartridge Driven by Pickup Head;

2. Ser. No. 13/838,075, filed Mar. 15, 2013, entitled: Linear/AngularCorrection of Pick-and-Place Held Component and Related OpticalSubsystem;

3. Ser. No. 13/838,762, filed Mar. 15, 2013, entitled: Auto-setupControl Process;

4. Ser. No. 13/839,239, filed Mar. 15, 2013, entitled: Virtual Assemblyand Product Inspection Control Processes; and

5. Ser. No. 13/839,790, filed Mar. 15, 2013, entitled: Pick-and-PlaceFeeder Module Assembly.

TECHNICAL FIELD

The present technology relates generally to the field of materialhandling, and more particularly to mechanisms and methods fortransporting small articles from a first location to a second location,as might be involved during precise placement of components onto aprinted circuit board.

BACKGROUND

Pickup, transport and precise placement of small articles normallyincludes use of a vacuum head for engaging and releasing the transportedarticle. Such apparatuses are commonly referred to as pick and placemechanisms.

Some pick and place mechanisms include a pneumatic cylinder which drivesa spindle mounting a vacuum head on a free end thereof. The spindle isadvanced and retracted as required along its own axis, to pick up orplace the articles (components), and is transported in a plane normal tothe axis of the spindle to move the components from one location toanother. Pneumatically operated devices are accompanied by substantialdisadvantages inherent in pneumatic operation. Some drawbacks are thedifficulty in monitoring the spindle position along its axis, andexcessive size, particularly when the component is quite small.

Known pick and place mechanisms include, for example, U.S. Pat. No.5,278,634 to Skunes, U.S. Pat. No. 6,145,901 to Rich, U.S. Pat. No.4,860,438 to Chen, U.S. Pat. No. 4,595,335 to Takahashi, U.S. Pat. No.4,151,945 to Ragard, U.S. Pat. No. 8,068,664 to Rudd and European patentapplication publication 0235045A2 to Universal Instruments Corporation.

SUMMARY

One exemplary pick-and-place machine feeds components from a supply tapecartridge advanced by a feeder gear mechanically rotated by the pickuphead, thus avoiding the need for the tape cartridge to have on-boardpower components. The pickup head includes a pickup device (e.g., avacuum nozzle) to pick up components from the tape as well as a rackgear to engage and drive the feeder gear of the supply tape cartridge.The pickup head also places components accurately on a substrate such asa printed circuit board (PCB).

The exemplary pick-and-place machine may include a component cameracooperating with a collimated light source arranged to projectcollimated light towards a component held by the pickup device and adiffuser screen disposed between the component and the component camerasuch that a shadow image of the held component is projected onto thediffuser screen. A linear correction and an angular correction of theheld component position are calculated in accordance with this shadowimage on the diffuser screen.

An exemplary pickup nozzle has an elongated hollow portion, a stopslidably disposed within the hollow portion, and a vacuum source influid communication with the hollow portion. The hollow portion isconfigured to simultaneously accommodate a plurality of picked-upcomponents as the internal stop is adjusted in the proximal direction. Acomponent can be ejected from the hollow portion and onto a substrate asthe internal stop is adjusted in the distal direction.

A computer program readable storage medium may store computer programcode structures including executable instructions that control at leastone computer processor programmed to control a pick-and-place machine inpicking up components from a feeder cartridge and then precisely placingthe components onto a substrate (e.g., to assemble a printed circuitboard). At least one pickup device may be selectively installed on thepickup head under such program control. Thereafter, the pickup head maybe controlled to advance a selected component supply tape. Amulti-purpose camera also mounted on the pickup head may read readableinformation on each feeder cartridge to obtain location and/oridentification information for each respective feeder component and usesuch data to better insure correct assembly of the printed circuit boardin accordance with the detected location and identification information.

Computer program code instructions may also control at least oneprocessor in virtually assembling a printed circuit board with aplurality of components to be provided on a substrate at predeterminedlocations. Individual images of the plurality of components are overlaidon an image of the substrate in accordance with the predeterminedlocations. An operator may confirm the location of each virtualcomponent placement to insure the proper location of each feeder withoutactually consuming any components.

A substrate having a plurality of components provided thereon (e.g.,held on the substrate with soldering paste) can also be inspected. Animaging device may capture an image of each component on the substrateand then group the images such that images of what is supposed to be thesame component type are grouped together so that one may readily detectwhether in fact the components installed on the substrate (a) are thesame component type; (b) are the intended component; and/or (c) wereinstalled with the correct orientation.

An exemplary feeder cartridge for a pick-and-place machine may include afeeder gear which acts to feed a tape through the feeder cartridge,wherein the feeder cartridge itself is without onboard provisions ofelectrical, mechanical or pneumatic power.

An exemplary feeder module for a pick-and-place machine may beinterchangeable with other feeder modules in the pick-and-place machineto reduce setup time. A user may configure in a feeder module a group offeeder cartridges for a particular job (e.g., assembly of a certainboard) and leave the feeder module undisturbed until the next time thatparticular board assembly is needed. Such modularity may allow a user tochange jobs in a matter of seconds.

Other aspects, features, and advantages of the present technology willbecome apparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, different aspects ofthis technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of variousembodiments wherein:

FIG. 1 is a perspective view of an example pick-and-place machine;

FIG. 2 is a perspective view of an example motion system of thepick-and-place machine of FIG. 1;

FIG. 3-1 is a perspective view of an example feeder module of thepick-and-place machine of FIG. 1;

FIGS. 3-2 a to 3-2 e are various views of example feeder modules of thepick-and-place machine of FIG. 1;

FIG. 4 is an enlarged detail of a portion of FIG. 3;

FIG. 5 shows an example removable feeder cartridge of the pick-and-placemachine of FIG. 1;

FIG. 6 is a perspective view of an example removable feeder cartridge ofthe pick-and-place machine of FIG. 1;

FIG. 7-1 is another perspective view of the removable feeder cartridgeof FIG. 6;

FIG. 7-2 a is a perspective view of another example removable feedercartridge of the pick-and-place machine of FIG. 1;

FIG. 7-2 b is another perspective view of the removable feeder cartridgeof FIG. 7-2 a;

FIG. 8 is a perspective view of an example cover film drive assembly ofthe pick-and-place machine of FIG. 1;

FIG. 9 is a side view of the removable feeder cartridge of FIG. 6;

FIG. 10 is an exploded perspective view of the removable feedercartridge of FIG. 6;

FIG. 11 is a perspective view of an example pickup head of thepick-and-place machine of FIG. 1;

FIG. 11 a is an enlarged detail of FIG. 11 showing an example forcesensing mechanism of the pick-and-place machine of FIG. 1;

FIG. 11 b is an exploded perspective view of the force sensing mechanismof FIG. 11 a;

FIG. 11 c is another exploded perspective view of the force sensingmechanism of FIG. 11 a;

FIG. 12 is a perspective view of a lower portion of the pickup headshown in FIG. 11;

FIG. 13 is a side view of the pickup head of FIG. 11 engaging a feedergear;

FIG. 14 is a perspective view of the pickup head of FIG. 11 showing anexample vacuum nozzle in a down position;

FIG. 15 is a perspective view of the vacuum nozzle shown in FIG. 14;

FIG. 16 is a perspective view of an example vacuum nozzle changercartridge of the pick-and-place machine of FIG. 1.

FIGS. 17 and 18 are perspective views of an example optical subsystem ofthe pick-and-place machine of FIG. 1;

FIGS. 19A to 20B are schematic representations of optical paths of theoptical sub-systems of FIGS. 17 and 18;

FIG. 21 is a perspective view of an example optional multi-componentvacuum nozzle system for the pick-and-place machine of FIG. 1;

FIG. 22 is an exploded perspective view of the multi-component vacuumnozzle system of FIG. 21;

FIG. 23 is an exploded top view of the multi-component vacuum nozzlesystem of FIG. 21;

FIG. 24 an exploded bottom view of the multi-component vacuum nozzlesystem of FIG. 21;

FIGS. 25-30 are various views of a vacuum nozzle of the multi-componentvacuum nozzle system of FIG. 21;

FIG. 31 is a perspective view of an example optional multi-componentvacuum nozzle system including pickup-head-mounted coils for inductivecoupling with the multi-component vacuum nozzle system;

FIG. 32 is a side view of the multi-component vacuum nozzle system ofFIG. 31;

FIG. 33 is a perspective view of an example optional multi-componentvacuum nozzle system including a pickup-head-mounted coil for inductivecoupling with the multi-component vacuum nozzle system;

FIG. 34 is a side view of an example optional multi-component vacuumnozzle system for the pick-and-place machine of FIG. 1;

FIG. 35 is a perspective view of an other example of a multi-componentvacuum nozzle system for the pick-and-place machine of FIG. 1;

FIG. 36 is an example electrical inductive coupling circuit for use withthe nozzles of the pick-and-place machine of FIG. 1;

FIG. 37 is a flow chart diagram of computer program code structure foran example “squaring” method used to provide linear and/or angularcorrections for component placement;

FIGS. 38-1 and 38-2 are example graphical representations of images of asubstrate and components to be placed on the substrate;

FIG. 39 is a schematic representation of an example virtual PCB havingthe component images of FIG. 38-2 placed onto the substrate image ofFIG. 38-1;

FIG. 40 is an example image representing a computer generatedpre-defined PCB;

FIG. 41 is representative of an example computer generated image of thevirtual printed circuit board of FIG. 39 overlaid onto the pre-definedPCB of FIG. 40;

FIG. 42 is an example schematic representation of a virtual PCB havingsome component images of FIG. 38-2 misplaced onto the substrate image ofFIG. 38-1;

FIG. 43 is representative of a computer generated image of the virtualPCB of FIG. 42 overlaid onto the pre-defined PCB of FIG. 40;

FIG. 44 is representative of a computer generated image of a finishedPCB image overlaid onto the pre-defined PCB of FIG. 40;

FIG. 45 is representative of an example operator display screen enablingfinished product inspection;

FIG. 46 is representative of an example operator display screenproviding information regarding components required for a PCB assembly;

FIG. 47 is a graph showing an example force vs. distance profile ofpickup device placing a component onto a substrate; and

FIG. 48 is a schematic representation of a laser engraver of thepick-and-place machine of FIG. 1.

DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES

The following description is provided in relation to several examples(most of which are illustrated) which may share some commoncharacteristics and features. It is to be understood that one or morefeatures of any one example may be combinable with one or more featuresof the other examples. In addition, any single feature or combination offeatures in any of the examples may constitute additional examples.

1.0 Pick-and-Place Machine

The example pick-and-place machine shown in FIG. 1 includes an outerframe 103 and a display 105 supported by the outer frame. The machine1000 further includes a pick and place head 200 arranged to pick up aselected component from feeder cartridges within feeder modules 300 andaccurately place the component on a substrate (e.g., a printed circuitboard (PCB)) (not shown in FIG. 1) located there below and positioned inan area between the opposing groups of feeder modules 300. The displayprovides a convenient interface for a machine operator.

Computerized control circuits are shown schematically in FIG. 1 asincluding at least one central processing unit (CPU) 110 connected toexecute computerized program code structures stored in memory 112 (e.g.,possibly in conjunction with a suitable overarching operating system asthose in the art will appreciate). Of course, CPU 110 also has access toany needed working memory 114, as well as suitable input/output (I/O)circuits 116. Indeed, display screen 105 may itself provide an I/O portfor operators (e.g., using a touch sensitive screen). A mouse, keyboardand/or other conventional I/O devices 118 may also be provided as willbe understood.

CPU 110 also has control of various light sources (e.g., LEDs) andoptical sensors 120 distributed throughout the pick-and-place machine1000 as will be described further below. In addition, the exemplarypick-and-place machine 1000 also has a multi-purpose camera 252 and acomponent camera 251 interfaced with CPU 110 and utilized as explainedbelow. Inductive coupling circuits 122 are also interfaced with CPU 110and utilized to control optical interfaces with vacuum nozzles as willbe explained. X/Y motor control 124 is also coupled to the CPU 110, asare control circuits 126 for controlling up/down pickup head motion andvacuum on/off valve control to the pickup head vacuum nozzle.

An X/Y motion system 400, shown in FIG. 2, is used to transport pick andplace head 200 between feeder modules 300 and a desired underlyingsubstrate location. Motion system 400 provides movement in both the Xand Y directions, thereby enabling pickup head 200 to be positionedadjacent any desired component pick-up locations (i.e., feedercartridges within feeder modules 300) and adjacent any desired placementlocations on the substrate. Once the pickup head is positioned in thecorrect x-y coordinate location, a crank mechanism (described later)inside pickup head 200 quickly raises or lowers the pickup headvertically to either pick up or place components.

Pickup head 200 is attached to a slider 455(1) that traverses a rail 423parallel to the X axis, A motor 403 rotates a screw shaft 413 that alsoextends in the X axis direction. A nut member 455 receives screw shaft413 and is also attached to slider 455(1) such that rotation of motor403 causes movement of nut member 455 along the screw shaft 413, therebycausing the pickup head to traverse the rail 423 in the X axisdirection.

Rail 423 is attached at its ends to respective nut members 445, 447. Nutmembers 445, 447 are each in turn connected to respective sliders445(1), 447(1). The sliders 445(1), 447(1) are arranged for movementalong respective parallel rails 424, 426 which each extend in the Y axisdirection. Two parallel screw shafts 414, 416 are arranged along the Yaxis direction such that each one of screw shafts 414, 416 extendsthrough a respective nut member 445, 447. Each screw shaft 414, 416 isconnected to a respective motor 404, 406 such that synchronous rotationof motors 404, 406 causes synchronized movement of nut members 445, 447along screw shafts 414, 416, thereby causing rail 423 (and thereforepickup head 200) to move in the Y axis direction.

Rails 424, 426 may be positioned on support members 462, 464 to providea stable, sturdy base for the motion system 400. Further, stabilizers463, 465 may extend between and connect support members 462, 464 toprevent relative movement between the support members.

Motors 403, 404, 406 may be conventional synchronized incrementallystepped servo motors using encoders for conventional position feedbackto enable precise positioning of pickup head 200 in the X/Y directions.

1.1 Feeder System

Now, with reference to FIGS. 3-10, an example feeder system will bedescribed. A feeder module 300 is shown in FIG. 3. Feeder module 300includes a frame 305 which supports a plurality of removable feedercartridges 350, as best shown in FIG. 4. The feeder module frameincludes two spaced-apart handle portions 307 and a front plate portion(or rail) 306 extending between handle portions 307. A reel-retainingportion 309 is positioned below the front plate portion 306. Thereel-retaining portion 309 includes a curved section arranged toremovably receive a plurality of tape-wound reels 330. Reel uprightsupports 381 may be slidably disposed in the reel-retaining portion 309so provide support to reels 330 to aid in keeping the reels upright.

The handle portions 307 facilitate an operator in positioning the feedermodule into, or removing the feeder module from, its operable positionin the pick-and-place machine 1000. Feeder modules 300 areinterchangeable. An aperture 314 in front plate portion 306 is arrangedto receive an alignment pin (not shown) that protrudes frompick-and-place machine 1000. The alignment pin serves to properly alignfeeder module 300 in the machine. The opposing end of front plateportion 306 may also include an aperture 314, as shown in FIG. 4. Frontplate portion 306 also includes a feeder module lock/ejection mechanism311 configured to lock feeder module 300 to the pick-and-place machine,as shown in FIG. 3. The feeder module lock/ejection mechanism 311 mayalso be actuated to eject the feeder module 300 from the machine 1000.Further, a plurality of alignment slots 398 may be formed in and extendacross a top portion of front plate 306 in a spaced arrangement, asshown in FIG. 3-1. Each alignment slot 398 is configured to engage amating portion of a feeder cartridge 350. Alignments slots 398 serve toproperly align and space feeder cartridges 350 in feeder module 300which in turn ensures that feeder cartridges 350 are properly aligned inpick-and-place machine 1000. A plurality of feeder modules 300 may bepositioned in the machine at any given time.

Alignment slots 398 may be spaced apart by 0.25 inches. A typical 8 mmtape feeder cartridge has a width of 0.5 inches, while 12 mm and 16 mmtape feeder cartridges have a width of 0.75 mm. Thus, by spacing thealignment slots 0.25 inches apart, 8 mm, 12 mm and 16 mm tape feedercartridges can be accommodated without gaps or wasted spaced between thefeeder cartridges.

The modular arrangement of feeder module 300 facilitates quick setuptime. For instance, a user can configure in a feeder module 300 a groupof feeder cartridges 350 for a particular job (e.g., assembly of acertain board). Feeder module 300 may be left undisturbed until the nexttime that particular board assembly is needed. Cost impediments to suchstrategy are removed by the relatively low cost of feeder cartridge 350,which is constructed from relatively inexpensive materials and designedwithout onboard provisions for power (as described below). In otherwords, a user can own significantly more feeder cartridges 350 ascompared to conventional feeders without adding significantly to thecost of pick-and-place machine 1000. A user may even dedicate a feedercartridge for each tape-wound reel 330. Feeder module 300 mayaccommodate up to 40 feeder cartridges, which may provide sufficientcapacity for complex assemblies while also facilitating portability.However, feeder module 300 may be configured to accommodate more than 40feeder cartridges depending on need.

An alternative feeder module 300-1 is shown in FIGS. 3-2 a to 3-2 e.Feeder module 300-1 includes a frame 305-1 which supports a plurality ofremovable feeder cartridges 350, as best shown in FIGS. 3-2 a and 3-2 b.Frame 305-1 includes two spaced-apart handle portions 307-1, a frontplate portion 306-1 extending between handle portions 307-1 and footportions 308 to engage a surface on which the feeder module ispositioned. A reel-retaining portion 309-1 is positioned below the frontplate portion 306-1 to accommodate tape-wound reels 330 below feedercartridges 350. Feeder module lock/ejection mechanism 311-1 may beconfigured to lock feeder module 300-1 to the pick-and-place machine.Frame 305-1 may be constructed from steel rod or other suitablematerials. Front plate portion 306-1 may be formed from aluminum orother suitable materials.

Reel-retaining portion 309-1 may include support members (e.g., a pairof spaced support members 393 (e.g., a pair of rods)) to support reels330, as best shown in FIG. 3-2 d. Support members 393 may be spacedapart by a distance relatively close to but smaller than a diameter ofreels 330. This arrangement prevents reels 330 from dropping through aspace between support members 393 while also containing the reels instable engagement with the support members.

Feeder module 300-1 may include a locking device 391 to lock reels 330in position in reel-retaining portion 309-1. Locking device 391 mayinclude a locking member 394 (e.g., a rod or bar) positioned near a topportion of reels 330, a pair of triggers 395 on opposite ends of thefeeder module to actuate the locking device, a pair of sleeves 362, apair of springs 397 (e.g., a helical spring), and a pair of pivot arms302 connecting locking member 394 to a respective trigger 395, as shownin FIG. 3-2 d. Each trigger 395 may include an actuating portion 395(1)(e.g., a user engaging portion such as a U-shaped member configured tobe displaced (e.g., by pulling) or otherwise actuated by the user) andan operating portion 395(2) (e.g., an elongate portion configured totransfer movement of actuating portion 395(1) to rotate arm 302 aboutpivot 399.

Locking member 394 may be connected to first end portions of pivot arms302. Second end portions of pivot arms 302 may be rotatably connected torespective operating portions 395(2) via an optional block 396 as thoseskilled in the art will understand. Each helical spring 397 may extendbetween block 396 and sleeve 362 such that operating portion 395(2)extends through an inner portion of the helical spring. By thisarrangement, spring 397 urges block 396 (and thus the second end portionof pivot arm 302 away from sleeve 362 (and toward front plate portion306-1) thereby causing operating portion 395(2) to move toward frontplate portion 306-1 and into an inserted position. When operatingportion 395(2) is urged towards the front plate portion, locking member394 is moved into a locking position, as shown in FIG. 3-2 d. In thelocking position, locking member 394 is positioned above reels 330 andrelative to support member 393 such that the reels are prevented (bylocking member 394) from being moved upward enough to clear the supportmembers. Thus, reels 330 are locked inside reel-retaining portion 309-1when locking member 394 is in the locked position shown in FIG. 3-2 d.

Reels 330 may be easily inserted into reel-retaining portion 309-1 bypressing each reel against locking member 394 (when in the lockedposition) until locking member 394 is displaced against a restoringforce of spring 397 a sufficient distance (FIG. 3-2 e) that the reel ispositioned in place in reel-retaining portion 309-1 and locking member394 snaps back into its locked position (FIG. 3-2 d). A bent tab 379prevents pivot arm 302 from pivoting past a vertical position therebypreventing reels from being removed by forceful pulling. Reels 330 arelocked in reel-retaining portion 309-1 in a manner that allows rotationof reels 330 as tape 340 is fed through feeder cartridges 350. That is,the reels, which, e.g., are formed of plastic, may slide against supportmembers 393 and/or locking member 394.

A user may pull trigger 395 away from front plate portion 306-1 againsta restoring force of spring 397 to cause locking member 394 to be movedto the unlocked position shown in FIG. 3-2 e in order to remove reels330 from reel-retaining portion 309-1.

It is noted that sleeve 362 may include an upright portion 362(1). Inanother example, the spring 397 may extend between the upright portion361(2) and pivot arm 302 (e.g., via block 396). Those skilled in the artwill understand and recognize that there are other suitable arrangementsfor arranging spring 397 in locking device 391. Furthermore, othersuitable locking arrangements may be used to secure reels 330 in feedermodule 300-1.

As shown in FIG. 3-2 b, guide member 303 may extend between feedercartridges 350 and reels 330 to guide the used tape 340 away from thereels so that the used tape does not get tangled in the reels.

Feeder module 300-1 may include rollers 301 configured to engage asurface of pick-and-place machine 1000 to facilitate insertion of thefeeder module into an operative position in the pick-and-place machine.Apertures 304 (e.g., tapered bores) may be disposed at opposite endportions of the feeder module, as shown in FIG. 3-2 b. Apertures 304 maybe configured to receive a mating pin on pick-and-place machine 1000 toalign the feeder module in the pick-and-place machine.

As shown in FIG. 4, a plurality of removable feeder cartridges 350 aremounted on front plate portion 306 of feeder module 300. A tape 340 fromeach reel 330 is fed through a respective feeder cartridge 350.Components to be placed on the substrate are contained on and/or in tape340. Feeder cartridges 350 serve to feed the component-bearing tape to acomponent pick-up location where the components are exposed for pick-upby pickup head 200. Feeder cartridges 350 are passive devices (as willbe described in more detail later) having no onboard provisions forpower (e.g., electrical, mechanical or pneumatic power). Tape 340 mayhave any suitable width as needed for a given component size (e.g., 8,12, 16, 24 mm or more).

The front plate portion 306 of frame 305 includes a first attachmentdevice (e.g., a protuberance 316, e.g., a rounded protuberance) along atop edge portion thereof and a second attachment device (e.g., a recess317) along a bottom edge. It is noted that the first and secondattachment devices may be partitioned (or otherwise divided) and thuseach configured as a plurality of first attachment devices and aplurality of second attachment devices corresponding to a respectivefeeder cartridge. As mentioned above, alignment slots 398 are formed inan upper portion of front plate portion 306. In an example, thealignment slots may be at least partially formed in protuberance 316.Protuberance 316 and recess 317 facilitate attachment of a feedercartridge 350 to front plate portion 306.

As best shown in FIG. 5, a body portion 352 of the feeder cartridgeincludes an upper attachment portion 352(1) which terminates in a firstconnecting device (e.g., receiving portion 352(1)a). Upper attachmentportion 352(1) includes alignment protrusion 363 on an inner surfacethereof. Alignment protrusion 363 may be configured with a shape thatmates with alignment slots 398. Referring to FIG. 7-1, body portion 352includes a lower attachment portion 352(2) having a second connectingdevice (e.g., projection 352(2)a) extending across an end portionthereof. Projection 352(2)a has an inclined or tapered surface 352(2)b.

To mount feeder cartridge 350 to frame 305, upper attachment portion352(1) may be placed over front plate portion 306 such that alignmentprotrusion 363 fits into a respective alignment slot 398 therebypositioning receiving portion 352(1)a around protuberance 316. A usermay then press down upon knob 365 which causes inclined surface 352(2)bto engage front plate portion 306 (e.g., locating member 317(1)) whichin turn causes lower attachment portion 352(2) to flex so as to causeprojection 352(2)a to snap into recess 317 of front plate portion 306.The snap-fit arrangement of lower attachment portion 352(2) and recess317 provides ease of installation. By this arrangement, feeder cartridge350 is supported at only one end by the front plate portion 306 offeeder module 300 thereby forming a cantilever. This arrangement allowsfor compact feeder cartridge and reel packaging. The cantilever mountingof feeder cartridge 350 allows access to a bottom portion of the feedercartridge. Therefore, reels 330 may be mounted below the feedercartridges and the tape 340 from each reel may be fed to a bottomportion of a respective feeder cartridge. Providing the feedercartridges and the reels in a stacked arrangement helps reduce thefootprint of the feeder module. In another example, feeder cartridge 350may be connected directly to pick-and-place machine 1000 in the mannerof a cantilever. Preferably, receiving portion 352(1)a and theprotuberance have mating shapes.

An example snap-fit arrangement may be described as “a mechanical jointsystem where part-to-part attachment is accomplished with locating andlocking features (constraint features) that are homogenous with one orthe other of the components being joined. Joining requires the(flexible) locking features to move aside for engagement with the matingpart, followed by return of the locking feature toward its originalposition to accomplish the interference required to latch the componentstogether. Locator features, the second type of constraint feature, areinflexible, providing strength and stability in the attachment.” TheFirst Snap-Fit Handbook, Bonenberger, 2000.

To remove a feeder cartridge, a user may simply push upwardly upon knob365 which causes front plate portion 306 to exert a force against lowerattachment portion 352(2) which in turn causes the lower attachmentportion to flex such that projection 352(2)a becomes disengaged withrecess 317.

Referring to FIGS. 5 to 7-2 b, a channel 365(1) is formed in knob 365such that an anti-tamper device may be fed through a group of feedercartridges. This allows a group of feeder cartridges 355 (e.g., groupedin a particular feeder module for assembly of a certain board) to be“put on the shelf” until the next time they are needed while ensuringthat the grouping of feeder cartridges is not changed.

Pick-and-place machine 1000 may include a detection device (e.g., anoptical interrupter 313 provided on front plate portion 306) to detectthe presence of feeder cartridge 350 in a properly installed position.Optical interrupter 313 includes spaced light emitting and lightdetecting portions as one skilled in the art will understand. Aprotruding portion 315 of body portion 352 is positioned to block thelight transmission of optical interrupter 313 (thus triggering theoptical interrupter) when feeder cartridge 350 has been inserted farenough that projection 352(2)a snaps into recess 317, thus confirmingproper attachment of feeder cartridge 350 to front plate portion 306. Afeeder cartridge 350 that is not inserted completely may have a raisedposition which may interfere with the pickup head. By the abovedescribed arrangement, feeder cartridge 350 will snap into place and beconsistently positioned with respect to front plate portion 306 eachtime the feeder cartridge is connected to the front plate portion.

Optical interrupter 313 may be used to determine when a feeder cartridge350 has been removed or when a new feeder cartridge has been added. Aswill be described later, the addition of a new feeder cartridge 350 mayprompt pick-and-place machine 1000 to acquire information from thefeeder cartridge.

In an alternative example shown in FIGS. 7-2 a and 7-2 b, front plateportion 306-1 may include a series of spaced guide channels 310 forreceiving protruding portion 315 of feeder cartridges 350. Each guidechannel 310 corresponds to a respective alignment slot 398-1 and willfurther ensure that each feeder cartridge 350 is properly aligned inpick-and-place machine 1000. As shown in FIG. 9, upper attachmentportion 352(1) may include a protrusion 364 to mate with alignment slots398-1 on front plate portion 306-1. Optical interrupter 313 may bedisposed within guide channel 310. Further, front plate portion 306-1may include an inclined surface 366 upon which inclined surface 352(2)bof projection 352(2)a may engage to facilitate attachment of feedercartridge to front plate portion 306-1. That is, in referring to FIG.7-2 b, as the user pushes downwardly on knob 365, feeder cartridge 350rotates in a clockwise direction as inclined surface 352(2)b slidesagainst inclined surface 366 until projection 352(2)a snaps into recess317. Additionally, as shown in FIGS. 7-2 a and 7-2 b, lower attachmentportion 352(2) may include a recessed portion to form a more pronouncedcatch 352(2)c to accommodate locating member 317(1).

Body portion 352 may further include a stabilizing portion 392 disposedbetween upper attachment portion 352(1) and lower attachment portion352(2) and configured to engage front plate portion 306-1 to stabilizefeeder cartridge 350. Stabilizing portion 392 may contact an engagingportion of front plate portion 306-1 disposed between protuberance 316and recess 317. Stabilizing portion 392 may include an extended flatportion configured to engage a flat portion of front plate portion 306-1for stabilizing the feeder cartridge by limiting movement between feedercartridge 350 and front plate portion 306-1. Those skilled in the artwill recognize that other mating surfaces may be used to limit movement.Receiving portion 352(1)a-1 may include an extending portion configuredto engage a surface of front plate portion 306-1 opposite protuberance316.

Referring to FIG. 5, tape 340 includes a plurality of sprocket holes341, a plurality of component pockets 343 to accommodate components (notshown), and a cover film 344 to contain the components in pockets 343until they are to be exposed for pickup. The cover film may be a thintransparent film lightly glued or heat sealed to tape 340 and/or thecomponents. As tape 340 is advanced through feeder cartridge 350, acover film drive assembly 359 peels the cover film from tape 340 (e.g.,see motion arrows on tape 340 in FIG. 5) to expose the components acrossa pickup zone 342.

A feeder gear 355 is rotatably disposed in feeder cartridge 350. Feedergear 355 is a passive gear relying on drive forces external of thefeeder cartridge 350 for rotation. Feeder gear 355 may be exposed frombody portion 352 to facilitate engagement with an external drivingdevice. However, in another example, feeder gear 355 may be recessedinto body portion 352 and accessible via a slot in the body portion. Asprocket wheel 356 (FIG. 5) is rotatable about a common axis with feedergear 355 and is locked in rotation with the feeder gear. As shown inFIG. 10, feeder gear 355 and sprocket wheel 356 may be rotatablydisposed on shaft 360. Pickup head 200 includes a rack gear that drivesthe feeder gear 355, as will be described later. As feeder gear 355 of agiven feeder cartridge 350 is driven (by pickup head 200), sprocketwheel 356 also rotates because of its locked arrangement with the feedergear. Sprocket teeth 356(1) engage sprocket holes 341 in tape 340 toadvance the tape through feeder cartridge 350.

Gear teeth 355(1) of feeder gear 355 engage cover film peeling gears357, 358 (FIG. 5) in cover film drive assembly 359 to cause cover film344 to be peeled away from tape 340. Specifically, gear teeth 355(1) offeeder gear 355 mesh with gear teeth 357(1) of cover film peeling gear357. Gear teeth 357(1), in turn, mesh with gear teeth 358(1) of coverfilm peeling gear 358. Cover film peeling gears 357, 358 are connected,respectively, to a pair of mating rollers 357(2), 358(2) which togetherfunction to pull cover film 344 and peel it from tape 340. In anotherexample, the feeder gear could drive cover film drive assembly 359 via abelt or other suitable device as those skilled in the art willrecognize.

As shown in FIGS. 6 and 7, feeder gear 355 includes calibration marks351 (e.g., corresponding to every other tooth), to enable the positionof the feeder gear to be precisely determined by CPU 110, as will bedescribed in more detail later. Calibration marks 351 may be hot-stampedwith a highly reflective foil (e.g., a white foil) to facilitate easyoptical detection. Alternatively, the marks may be stamped with a silveror gold colored foil, for example. Calibration marks 351 may be arrangedon feeder gear 355 in a manner that matches the component spacing ontape 340 such that the calibration marks may also identify a location ofcomponents on tape 340 as well.

Turning back to FIG. 4, a series of light emitting diodes (LEDs) (e.g.,multi-colored LEDs 312) extend across front plate portion 306. Frontplate portion 306 (or another part of feeder module 300) may includethrough holes or channels to permit the LEDs to optically communicatewith light pipes 354 (e.g., formed of translucent or transparentplastic) disposed on each feeder cartridge 350. Since feeder cartridges350 do not require electrical power, light (i.e., LEDs 312) produced bypick-and-place machine 1000 may be selectively fed to light pipes 354 toderive a status of each feeder cartridge 350. The light may be visibleto an operator through a button 354(1) at a top portion of light pipe354.

Now referring to FIGS. 6, 7 and 9, body portion 352 of feeder cartridge350 includes an inlet guide channel 384 through which tape 340 is guidedto pickup zone 342. Inlet guide channel 384 is formed by opposing wallportions 384(1), 384(2), as best shown in FIG. 9. Once cover film 344 ispeeled from tape 340, the remaining portion of the tape (aftercomponents are removed) is fed out of the feeder cartridge through anoutlet guide channel 386. As shown in FIG. 9, outlet guide channel 386is formed by opposing wall portions 386(1), 386(2). Similarly, peeledback and used cover film 344 is guided out of the feeder cartridge 350by a cover film guide channel formed by opposing wall portions 388(1),388(2).

An alternative cover film drive assembly 370 is shown in FIGS. 6-10. Asbest shown in FIG. 8, cover film drive assembly 370 includes first andsecond cover film peeling gears 371, 372 having mating gear teeth371(1), 372(1). First gear 371 is connected to and driven by a thirdgear 373. Referring to FIGS. 8 and 10, third gear 373 has gear teeth373(1) that engage gear teeth 355(1) of feeder gear 355 such that thirdgear 373 is driven by feeder gear. As best shown in FIGS. 6 and 8, coverfilm 344 is fed between mating first and second gears 371, 372 such thatrotation of feeder gear 355 causes the peeled back cover film to bedrawn between first and second gears 371, 372 thereby peeling the coverfilm from tape 340. The mating teeth 371(1), 372(1) drive the cover film344; however, it is noted that the cover film 344 is intended to slip ata modest force through the teeth 371(1), 372(1). Alternatively, one ofthe first and second gears 371, 372 may instead be a roller (e.g., arubber roller).

The second gear 372 may be supported on a tensioner arm 380. A lowerportion of tensioner arm 380 includes a shaft opening 380(1) thatrotatably receives shaft 382 (FIG. 10) which protrudes from body portion352. Second gear 372 is attached to an upper portion of tensioner arm380. When tape 340 is initially fed through feeder cartridge 350, anoperator may peel cover film 344 from a leading edge of tape 340 andfeed a leading edge of the cover film through cover film drive assembly370, as an initial set-up procedure. Tensioner arm 380 enables secondgear 372 to be rotated away from first gear 371, thereby providingsufficient space to easily place the leading edge of cover film 344between first and second gears 371, 372. Once the leading edge of thecover film is in place between the first and second gears, tensioner arm380 may be rotated toward first gear 371 to pinch the cover film betweenfirst and second gears 371, 372. Tensioner arm 380 may be urged towardthe cover film by a spring (e.g., a helical torsion spring (not shown)connected to the shaft 382).

The tensioner arm 380 may include a knob 380(3) to assist the operatorin pivoting tensioner arm 380. Knob 380(3) protrudes upwardly from bodyportion 352 through opening 353 in the body portion.

In another example, first and second gears 371, 372 may each includeseparable portions, as shown in FIG. 10. For instance, first gear 371may comprise a first portion 371(a) and a second portion 372(b) disposedon opposite sides of body portion 352 and connected to one anotherthrough opening 352(3) formed in body portion 352. Similarly, secondgear 372 may comprise a first portion 372(a) and a second portion 372(b)disposed on opposite sides of tensioner arm 380 and connected to oneanother through opening 380(2) formed in the tensioner arm. A shaftportion may protrude from one portion of first and second gears 371, 372to connect to the other portion.

Body portion 352 may include opposing curved portions 390 to assist indirecting the cover film to cover film drive assembly 370. The curvedportions may be tapered to more precisely direct the path of the coverfilm.

As shown in FIGS. 6 and 7, a feeder cartridge 350 may include a label(e.g., on the body portion 352). Label 361 may include a machinereadable barcode (or other machine readable markings), as well as humanreadable alphanumeric text (which may, of course, also be machine readand recognizable). The barcode may be read by a multi-purpose camera onpickup head 200, as will be described later, to convey to pick-and-placemachine 1000 (e.g., CPU 110) information (e.g., a part number) regardingthe particular components being fed by that particular feeder cartridge.Additionally, as a confirmation, the operator may simply read thealphanumeric text on label 361 to ensure that the component identifyinginformation (e.g., a part number) on the label matches the componentidentifying information (e.g., a part number) on reel 330 containingtape 340 being fed through feeder cartridge 350.

Turning back to FIG. 4, in an example, four color LEDs (e.g., greenblue, red and yellow LEDs 312) may be used. The light pipe 354 of anewly installed feeder cartridge may blink yellow until label 361 isread. If label 361 is successfully read, the light pipe may show thegreen or blue light. The green light may indicate that all is ready togo while the blue light may indicate that the feeder cartridge is readybut not used in the current program (assembly). Thus, the blue lightmight indicate an “incorrect” feeder cartridge for the current assemblyor simply that the feeder cartridge is needed for a later assembly. If afeeder cartridge has no label or a label that is not readable, lightpipe 354 will show red. During an assembly process, the blue light mayindicate to a user which feeder cartridges 350 can be removed withoutaffecting the current assembly. This facilitates change-over to a newassembly.

Further, light pipe 354 of a feeder cartridge may blink (e.g., red) whenthe feeder cartridge will be empty in a certain amount of time (e.g., 20minutes) at the current rate of production. The light may blink at afaster rate as the feeder cartridge approaches an empty status (e.g., 5minutes until empty). This may alert a user to prepare a new reel ofcomponents for reloading, or the user may simply install a backup feedercartridge to allow the machine to revert to the backup teeder cartridgeupon depletion of the primary cartridge. Light pipe 354 of the primaryfeeder cartridge may then show red to indicate an empty status.

The feeder cartridge 350 parts (e.g., body portion 352, feeder gear 355,sprocket wheel 356, and cover film drive assembly 359, 370) arepreferably formed of plastic (e.g., injection molded plastic).

1.2 Pickup Head

Referring to FIGS. 11-14, the pickup head 200 of the examplepick-and-place machine 1000 is shown. Pickup head 200 includes a frame204. A controller (e.g., printed circuit board 202) for controlling thepickup head 200 is attached to the frame 204. The frame includesopposing sidewalls 204(2), 204(3). Each sidewall 204(2), 204(3) mayextend continuously or may include offset portions in the manner ofsidewall 204(3) which has an inwardly offset upper portion. A frontlower wall portion 205 extends between front portions of the sidewalls204(2), 204(3) and a rear lower wall portion 207 extends between rearportions of sidewalls 204(2), 204(3).

A gear driving mechanism 210 is disposed at a lower portion of pickuphead 200 and is rotatably connected to the front and rear lower wallportions 205, 207. As best shown in FIG. 12, gear driving mechanism 210includes a pair of parallel arms 212, 214. The arms 212, 214 arerotatably connected to lower wall portions at pivot 217. Arms 212, 214may be formed of any suitable material, but are preferably formed ofaluminum, A1 stainless steel or brass.

A rack gear 216 is connected to the free ends of arms 212, 214 such thatthe rack gear extends between the arms. Rack gear 216 may be formed ofany suitable material, but is preferably formed of aluminum, A1stainless steel or brass. The rack gear has one or more gear teeth216(1) that mesh with the gear teeth 355(1) of the feeder gear 355 of aparticular feeder cartridge that happens to be aligned with it. That is,arms 212, 214 are configured to rotate downwardly to cause rack gear 216to mesh with feeder gear 355 when the pickup head 200 is so positionedat a particular selected feeder cartridge 350, as best shown in FIG. 13.Once rack gear 216 is engaged with feeder gear 355, the pickup head maybe moved in the Y axis direction by motion system 400 to drive feedergear 355 and thereby index (i.e., move) tape 340 to bring the nextcomponent into pickup zone 342. The motive power required for the feedercartridges is thus supplied as needed by the pickup head 200, avoidingthe need for a drive motor in the feeder cartridge (or feeder module)itself.

The gear driving mechanism 210 includes an optical sensing system (e.g.,reflective sensors) to read the calibration marks 351 on the engagedfeeder gear 355. In the illustrated example of FIG. 12, gear drivingmechanism 210 includes two sensors (e.g., LED/phototransistor sensors)218 on opposing ends of rack gear 216. The two sensors 218 are alsodisposed on opposite sides of rack gear 216. The sensors 218 include anLED arranged to emit light toward feeder gear 355. A phototransistorelement is also included in each sensor 218 to detect whether or not theemitted light is reflected, as one skilled in the art will understand.As such, sensors 218 are able to precisely detect the rotary position offeeder gear 355. As shown, sensors 218 are oppositely directed thuspermitting one to be used when the feeder gear is on one side of pickuphead 200 and the other sensor 218 to be used when the feeder gear is onthe other side of pickup head 200.

Optical sensors 218 may also be used to measure the gear position in thelateral (x) axis direction, as determined by a distance from one of thesensors 218 to feeder gear 355. Sensor 218 has a relatively narrow range(distance) over which the sensor can detect reflected light. Theresponse signal amplitude peaks at a specific distance from feeder gear355 and falls quickly at greater or lesser distances from that pointthus making it possible to identify an optimal distance relative to thepeak amplitude point. One skilled in the art will recognize that a“valley” instead of a peak of the signal amplitude may be used. Movingsensor 218 until the response has a predetermined amplitude relative tothe peak amplitude will identify the lateral position of the gear(distance from feeder gear 355 to sensor 218). Since feeder gear 355,sprocket 356 and tape 340 are connected to one another, the measuredlateral position of feeder gear 355 can be used to further determine thelocation of pickup zone 342 as well as a component to be picked. Thispeak/distance sensing operation may be done on the fly. For example, theprocess can be performed by starting with sensor 218 in relatively closeposition to feeder gear 355 and then moving the sensor away from thefeeder gear, or alternatively, starting with sensor 218 relatively faraway and then moving the sensor closer to the feeder gear, while notinga peak in the amplitude and the position where the peak occurred—thepeak being at a known distance relative to a desired optimum distance.

The rotary position of feeder gear 355 can be used to determinecomponent location in the Y axis direction, while the lateral positionof the feeder gear can be used to determine component location in the Xaxis direction. This information is used by the pick-and-place machine1000 to refine its determined location of pickup zone 342. Knowledge ofthe exact X axis location of pickup zone 342 can be used to mitigate orcancel the effects of feeder lateral location misalignment. Similarly,knowledge of the exact Y axis location of pickup zone 342 can be used tomitigate or eliminate the effects of errors caused by mechanical slop orlash in the drive gear train.

Sensor 218 includes an LED to emit light and a photosensor to detect thereflected light. However, one skilled in the art will understand thatthe LED may serve the dual functions of emitting light and sensing (nowoperating as a photodiode) reflected light. Such arrangement may reducethe space required by sensors 218 on the gear driving mechanism 210.

An electromechanical solenoid 220 is positioned in pickup head 200, asbest shown in FIG. 11. Electromechanical solenoid 220 may be actuated tolower an engaging element (e.g., a roller) 222 which engages arm 214 andpushes it downwardly about its pivot to cause the gear driving mechanism210 to be lowered. In other examples, an air cylinder or motor (e.g., alinear motor) may be used instead of electromechanical solenoid 220.Gear driving mechanism 210 may be returned to its original position by aspring (as depicted) or other suitable device.

Referring to FIGS. 11 and 14, pickup head 200 includes a pickup device(e.g., vacuum nozzle 230) that functions to pick up a component from aselected tape 340 and then place that component onto the substrate (notshown) at a precisely determined location and in a precisely determinedorientation. Although vacuum nozzle 230 is shown in the illustratedexample, it is noted that other methods of picking up and placing acomponent may be used. For example, grippers may be actuated (e.g., by avacuum pressure driven piston) to pick up components and place thecomponents on a substrate. Magnetic components may be picked up with anelectro-magnet. An adhesive could be used to pick and place components.Other examples include state change adhesion (e.g., freezing water intoice), AC magnetic induction (which may attract non-magnetic componentsif they are electrically conductive), jet entrainment (which may be usedto pick and place components by pressure), and electro-static charge.

As shown in FIG. 11, vacuum nozzle 230 is suspended from nozzle holder231. Vacuum nozzle 230 is removably attached to nozzle holder 231.Nozzle holder 231 is connected at its upper end to a shaft of nozzlerotation motor 234. Vacuum nozzle 230 is in flexible fluid communication(e.g., a flexible tube) with a vacuum generator via nozzle holder 231 soas to provide vacuum/suction at a distal opening of vacuum nozzle 230.The vacuum is provided so that a component may be picked up and heldagainst the distal nozzle end by vacuum force (i.e., actually bydifferential air pressure forces on the top and bottom of the componentcaused by the vacuum at the distal end of the nozzle) while in transitbetween the feeder cartridge and the substrate.

Nozzle rotation motor 234 is positioned on a top side of platform 232opposite nozzle holder 231. Nozzle rotation motor 234 serves to rotatevacuum nozzle 230 so as to adjust an angular position of a componentpicked-up/held by vacuum nozzle 230. Nozzle rotation motor 234 ispreferably a servo step motor using a conventional position feedbackencoder to provide precise rotary adjustment of vacuum nozzle 230.

Vacuum nozzle 230 is quickly raised and lowered by a crank mechanismconnected to platform 232, e.g., via a force sensing mechanism 800 whichwill be described later. Crank arm 240 is connected to connecting rod242 which extends downwardly to connect to platform 232. Crank arm drive246 (e.g., a servo-controlled rotary motor) is arranged to rotate crankarm 240, thereby causing connecting rod 242 to raise or lower vacuumnozzle 230. When platform 232 is raised or lowered, nozzle rotationmotor 234 is also raised or lowered along with platform 232. Platform232 is arranged to slide along vertical guide rail 239 positioned onrear wall 204(1) of frame 204. Instead of a crank mechanism, vacuumnozzle 230 may be raised and lowered by other devices, such as a motordriven lead screw of a voice coil linear motor.

As can be seen in FIG. 11, the platform extends to a side portion ofpickup head 200 to support a camera assembly 250. As such, cameraassembly 250 is also raised or lowered with the platform, as can be seenin FIG. 14 where pickup head 200 is in a down position. Vacuum nozzle230 is arranged to either pick up a component from a selected tape 340or place a component on the substrate at a selected position when thevacuum nozzle is in the down position shown in FIG. 14.

As shown in FIG. 15, vacuum nozzle 230 includes flange 230(1), neckportion 230(2) and distal nozzle opening 230(3). Projection 238 andnotch 237 permit controlled accurate indexed positioning of the vacuumnozzle 230 on pickup head 200 and/or a nozzle changer cartridge.Specifically, projection 238 may be used to align vacuum nozzle 230 innozzle holder 231 and the notch 237 may be used to align the vacuumnozzle in a nozzle changer 270 (discussed below). Information as tonozzle type and/or identity can be encoded by fiducial markings 233, 235(e.g., reflective/non-reflective and/or color-coded markings).

A nozzle changer cartridge 270 is shown in FIG. 16. The nozzle changercartridge may house a variety of vacuum nozzles, including differentlysized vacuum nozzles. Nozzle size may correspond to the size ofcomponents contained on a particular tape 340 (e.g., a larger vacuumnozzle may be required for larger components). The nozzle changercartridge is arranged in the pick-and-place machine 1000 in an areaaccessible to pickup head 200. In this manner, pickup head 200 may belowered at a selected position to cause nozzle holder 231 to attach to adesired vacuum nozzle (or to deposit a presently attached vacuum nozzleinto an empty cavity of the nozzle changer cartridge). Then, theselected vacuum nozzle 230 may be unlocked from the nozzle changercartridge 270 by shifting locking plate 273 from alignment of nozzleswith the small opening 272 to alignment of nozzles with the largeopening 274 of the nozzle changer cartridge 270. Locking plate 273 maybe driven back and forth (e.g., with a solenoid, air cylinder or motor).

The multi-purpose camera in pickup head 200 may be used to read thefiducial markings 233, 235 on vacuum nozzle 230 so as to selectivelyposition the pickup head for pickup of a desired vacuum nozzle and/orfor deposit of a vacuum nozzle in a currently empty position of thenozzle changer cartridge 270. CPU 110 may also be programmed to maintaina table or other data to record the identity of vacuum nozzles inparticular changer cartridges positions, open positions in the changercartridge, and the like.

Fiducial marks 271 (e.g., round dots) on the nozzle changer cartridge270 are used to locate the precise installed location of the changercartridge. Other information may be encoded by fiducial size orlocation, such as changer type, number of positions, etc. An opticalinterrupter (not shown) may be positioned internally to report when auser opens the changer cartridge 270 (e.g., to change the nozzleconfiguration). The system will be prompted to re-read fiducial markings233, 235 on the vacuum nozzles if changer cartridge 270 is opened. Oncethe changer cartridge is open, the system may maintain the changercartridge in the open position for the user's convenience.

1.3 Dual Camera Assembly

The pickup head 200 employs a dual camera assembly 250 to provide forcomponent centering and a variety of other imaging control functions.Referring to FIGS. 17 and 19A to 20B, dual camera assembly 250 includesside-facing component camera 251 to capture a shadow image (silhouette)of a component held on vacuum nozzle 230. Component camera 251facilitates angular adjustment of the component as well as linearadjustment, i.e., positioning of the component. Dual camera assembly 250also includes a down-facing multi-purpose camera 252 to capture imagesof the substrate, read barcode labels (e.g., on the feeder cartridges350), image calibration marks (e.g., on the machine 1000) and performother imaging functions. Cameras 251, 252 are preferably high resolutionmonochrome cameras.

Component camera 251 and the multi-purpose camera 252 share a singlelens 250(1) via beam splitter 250(2), as best shown in FIG. 19A. Thelens 250(1) is preferably an ordinary lens intended for ordinary (nottelecentric) camera imaging. Light passing through lens 250(1) isdirected to both component camera 251 and multi-purpose camera 252 by abeam splitter 250(2). However, in the exemplary embodiment, componentcamera 251 and the multi-purpose camera 252 are not required to be usedat the same time.

The dual camera assembly 250 also comprises a conventionalmicroprocessor/controller subsystem (not shown) and video capturehardware (not shown) to interface the cameras 251, 252 and themicroprocessor/controller subsystem ultimately to the at least onesystem CPU 110.

1.3.1 Component Camera

Referring to FIGS. 17-19A, light from a light source (e.g., LED orlaser) 253 is delivered to component camera 251 via mirror 255,collimating lens 257, component C, diffuser screen 259, beam splitter260, lens 250(1) and beam splitter 250(2). Light source 253 projectslight 253(1) downwardly to mirror 255, as best shown in FIG. 19A. Themirror reflects the light through collimating lens 257 and then towardsdiffuser screen 259. Mirror 255 and collimating lens 257 may becontained in housing 257(1), as shown in FIG. 18. Additionally, supportstructure 259 a may support the diffuser screen. Light 253(1) emergingfrom diffuser screen 259 enters conventional beam splitter 260 and isdirected upwardly to camera lens 250(1), as best shown in FIG. 19B.Finally, light 253(1) enters component camera 251 by way of beamsplitter 250(2).

When the component C is picked up by vacuum nozzle 230, the vacuumnozzle is raised to the up position within pickup head 200, as shown inFIG. 18. Such positioning brings the component C, which is held againstthe nozzle opening 230(3), into the path of light 253(1), as shown inFIG. 19A. The collimated light projects a clearly focused shadow of thecomponent C onto diffuser screen 259. Use of a diffuser screen 259between component C (illuminated by collimated light) and componentcamera 251 provides essentially an unlimited depth of field.

A component C as held against the distal nozzle opening 230(3) istypically not exactly centered with respect to the nozzle opening. Thus,to ensure accurate placement of the held component on the substrate, analignment correction must be calculated before the component is placed.The shadow image of the component on diffuser screen 259 is used toobtain this correction.

Squaring Method

In an example, a position adjustment routine, or “squaring method,” asdescribed below with reference to FIG. 37, may be used to obtainalignment correction of component C.

The component angle as actually held by the nozzle is measured byrotating the component C to a test angle of 22.5 degrees on either sideof a nominal predetermined normal angle, as represented by steps 601,602. Measurements begin with the narrow side of the component facing thecamera. This orientation will result in the largest shadow length changefor a given rotation. The squaring scale factor number is based on thisorientation and the measurement does not work if the long dimensioninitially faces the camera. This problem does not exist with squaresymmetrical components. If the picked-up component is rotationallymisaligned by 5 degrees, for example, the test rotations would yieldactual orientation angles of 22.5-5 and 22.5+5 degrees, therebyresulting in component angles of 17.5 degrees and 27.5 degrees.

By measuring both directions a greater difference in the resultingsilhouette length (angles) is available, which enhances precision.Because the ratio of these values is employed, the actual magnitude ofthese values, or in other words the size of the part, is irrelevant. Inaddition, this makes certain forms of image distortion and non-linearityself cancelling.

The ratio of the lengths of the horizontal shadows is related to thecomponent angle. If the ratio is smaller than 1, the inverse of theratio is used, and in either case, 1 is subtracted. This results in anumber that increases as the component angle increases. The relationshipto actual angle depends on the aspect ratio of the component(width/length), but is independent of size. The ratio is nearlyproportional to angle, but has a small downward slope decreasing about15% between 1 and 10 degrees. An equation is used to better fit theslope. For example, K-ratio*K/2.4+4.2 works well over a good range ofcomponent sizes, where K is the scale factor of a rotation of 10degrees. The value K is typically 20-40 and may be calculated in advanceif the component dimensions are known. The derivation process for Krotates the coordinates of the component as determined by the givendimensions (e.g., 10 degrees via trigonometry), then figures the ratioof the silhouette lengths and derives the scale factor that wouldconvert the ratio to 10 degrees.

The component angle calculated by this procedure, as represented by step603, will first be used to align the component to measure its linearmisalignment. In step 604, the component is rotated back from the testangle (22.5 degrees) to the nominal predetermined normal angle (but inaddition accounting for the calculated error angle) which aligns thenarrower side of the rectangular component parallel to the camera. Thisrotational orientation is equivalent to an orientation the componentwould have had if the component was initially picked up with zero error.The left edge of the camera image is used as the reference point formeasurements.

The fundamental unit of video measurement is the sensor pixel. Aresolution of 0.001 inches per pixel is suitable. However, themeasurement resolution is not limited to the size of a single pixel. Thepixel intensity may be used to infer the actual edge position of thecomponent, thus effectively increasing the available resolution. This iscommonly known as sub pixel imaging, or sub pixel interpolation. Toreduce the effect of “image noise,” measurements from several sequentiallines may be averaged. In step 605, the pixel counts from the left edgeof the image to both left and right edges of the component silhouetteare measured. The center of the component is found by averaging thesetwo values, in step 606. Center=(L+R)/2. The difference between thecomponent center and the pickup spindle (nozzle holder) center is alinear error that must be corrected. In step 607, the component is thenrotated 90 degrees and then, in step 608, the process is repeated tofind the error on the other axis. The outcome of this process is both alinear X/Y correction and an angular correction, as represented by step609. This will be applied to the spindle (nozzle holder) position justprior to the component being placed.

Averaging may be applied to the squaring process. That is, data fromother scan lines in the component image may be employed. Specifically,several values of L from sequential scan lines may be averaged toproduce a “cleaner” L. This process may also be used for R. Then, asingle (L+R)/2 calculation may be performed, or alternatively, several(L+R)/2 calculations may be carried out with several raw L and R values,and then the (L+R)/2 results may be averaged to produce a cleaner(L+R)/2 result. When several data points are available, artifactrejection may also improve the quality of the resulting calculations.Data points that lie relatively far away from the others may be rejectedas defective so as to not contaminate the result. This process caneliminate the influence of measurement noise or physical contaminationsuch as dust in the image.

In addition to the center of the component, (R-L) may be calculated todetermine the component length. Also, by counting the scan lines in thesilhouette, the thickness of the component may be determined.

1.3.2 Multi-Purpose Camera

Referring to FIGS. 17, 18, 20A and 20B, light from a light source (e.g.,a multi-color LED array) 254 is delivered to multi-purpose camera 252via diffuser 256, beam splitter 260, lens 250(1) and beam splitter250(2). Light source 254 projects light 254(1) through diffuser 256 andinto beam splitter 260 which passes part of the light and directs theother part of the light downwardly to substrate 258, as best shown inFIG. 20A. As can be seen in FIG. 20B, substrate 258 reflects the lightback through beam splitter 260 and then to multi-purpose camera 252 byway of lens 250(1) and beam splitter 250(2).

The light that passes through beam splitter 260 may hit diffuser screen259 and/or its mounting frame and be reflected back to beam splitter 260which will reflect part of the light up to multi-purpose camera 252. Thelight being reflected off of diffuser screen 259 may create anundesirable ghost image on the diffuser screen which will overlay andinterfere with the image of the substrate 258. In an example, anantireflective device (e.g., an antireflective coated circular polarizer259(1)) may be installed between diffuser screen 259 and beam splitter260. In the illustrated example, antireflective coated circularpolarizer 259(1) is applied (e.g., glued) to diffuser screen 259. Theantireflective coating prevents ghost reflections from its front surfaceas those skilled in the art will understand. The circular polarizerpolarizes incoming light before it strikes diffuser screen 259. Thus,the light reflected off of diffuser screen 259 will have an oppositepolarization to that allowed through the circular polarizer, therebysuppressing reflections.

Unlike the component camera 251, which may have a fixed focus due to itsfixed vertical movement with the vacuum nozzle 230 (and therefore theimaged component), multi-purpose camera 252 has a variable focus due toits relative vertical movement with respect to substrate 258. Thevariable focus ability of multi-purpose camera 251 enables the camera toperform a variety of imaging functions.

Multi-purpose camera 252 is arranged to image the substrate (or vacuumnozzles, feeder cartridges, etc. located beneath pickup head 200).Multi-purpose camera 252 may also provide close-up images of componentsplaced on substrate 258. Multi-purpose camera 252 may also imagecalibration marks provided on machine 1000 (e.g., on a base or supportportion). Further, the camera can read barcode labels (e.g., label 361)on feeder cartridges 350. The multi-purpose camera 252 may also measurefeeder cartridge 350 location targets (fiducial marks) (e.g., a round orsquare dot) on the feeder cartridge (e.g., on upper attachment portion352(1)) to update the system with actual feeder location values. Each ofthese imaging functions is likely performed at a different focusdistance.

Additionally, with a reverse periscope mirror system (not shown),multi-purpose camera 252 may serve the function of an up-facingcomponent camera utilized to obtain alignment correction of component C.This is particularly useful for large integrated circuit packages (e.g.,greater than 0.75 inch), which are typically imaged by an up-facingcamera.

1.4 Force Measurement

Utilizing control of a “touch” force of nozzle 230 when picking orplacing a component (part) allows significant advantages. Particularly,with a crank driven nozzle, the below described system allows a clean,“noise” free measurement of the actual force component of the crankdrive movement. The oscillatory nature of the crank provides force in aconstantly changing direction. Measuring stress in the crank arm itselfwould produce a value contaminated by force components that do not alloperate on the part being picked or placed. Indeed, some of these forcecomponents are used to accelerate the crank system. The challengeultimately amounts to isolating the vertical component from all of theother components and identifying an amount of the force that iscontributing to acceleration/deceleration of the crank structure, andfurther, the amount of the force that is imparted to the picked orplaced part itself.

The vertical component of force is isolated by a flexible mechanicalstructure akin to a door hinge, which is described below in relation toFIGS. 11 a to 11 c. A typical door hinge allows free motion of the doorto allow passage in/out while not allowing the door to move up/down orside-to-side. That is, the hinge offers solid resistance to up/down,left/right forces while allowing the door to swing freely in theoperative axis. Similarly, a long thin flexible structure in the crankarm terminating structure functions in this manner. Motion of thisstructure in the flexure axis is measured by a force sensing chip thatdeflects a relatively small amount (e.g., 0.0001 inch) for the forcesencountered. Force magnitude is conveyed as an analog voltage. Theflexible structure is spring loaded to a midscale value and forces in anupward direction on the nozzle unload the spring loaded flexiblestructure. Thus, in the event of an unanticipated impact with thecircuit board the sensor is unloaded, rather than overloaded, to preventdamage. The force reported by this system is the sum of nozzle touchforce and acceleration/deceleration forces.

A 3-axis accelerometer may be mounted on the moving structure to reportvertical acceleration as an analog voltage. Thus, (acceleration) forcemay be derived from the acceleration using F=ma. The touch force is thencalculated by subtracting the acceleration force from the total force.This measured force may be used to create a force-distance profile thatcan identify the absence or presence of solder paste, as described belowin relation to FIG. 47. The force-distance profile may report themeasured force over a traveled distance of nozzle 230. Particularly, aforce vs. distance profile may be analyzed and compared (e.g., with acontrol processor) to a predetermined force vs. distance profile todetermine the presence or absence of solder paste.

An example force sensing mechanism 800 is shown in FIGS. 11 a to 11 c.As best shown in FIGS. 11 b and 11 e, force sensing mechanism 800includes housing 802, a plate (e.g., circuit board 810), and spring 809connected to housing 802 and circuit board 810 in tension so as to pullthem towards one another. Housing 802 includes tab 804 on a first sidethereof which connects to connecting rod 242 at drive point 804(1). Apair of wall portions 802(1) extends from tab 804 and each includes acutout 802(2) therein so as to form a hinge 808 (e.g., a thin flexiblehinge). Flexing wall 807 extends upwardly from hinge 808 and terminatesin an attachment portion 806. By this arrangement, force sensingmechanism 800 is flexible in response to forces in the direction of theoperative axis and maintains rigidity in response to forces in thedirections of the other axes.

Attachment portion 806 is attached to platform 232, for example byscrews extending through screw holes 806(1). Thus, circuit board 810 andhousing 802 are permitted to move relative to one another by movement offlexing wall 807 via hinge 808. That is, for example, an upward force onnozzle 230 may cause housing 802 to move toward circuit board 810 asflexing wall 807 rotates outwardly. Such movement may be measured byforce sensor 812 (e.g., a semiconductor and strain gauge on circuitboard 810) to determine a magnitude of the upward force on nozzle 230.An adjustable member (e.g., a screw) may be attached to housing 802 andextend through aperture 816 to a position adjacent contact point 814such that the screw presses upon contact point 814 when housing 802moves closer to circuit board 810 to provide a force input to forcesensor 812. Circuit board 810 may rest on a recessed portion 818 formedin attachment portion 806 such that the circuit board lies belowplatform 232.

As the nozzle is moved downwardly, housing 802 will tend to move awayfrom circuit board 810, thus diminishing the measured force. On theother hand, when the nozzle is moved upwardly, housing 802 will tend tomove toward circuit board 810 thereby increasing the measured force.

1.5 Laser Engraver

Pickup head 200 may also include a laser to engrave substrate 258 (e.g.,PCB) with part information, date of manufacture, or other information.

Referring to FIG. 48, a laser 900 (e.g., a laser diode) may be mountedon pickup head 200. Lens 902 may also be mounted on pickup head 200 tofocus and concentrate the laser energy onto a small spot on a surface ofthe board. Lens 902 may include a single element, or alternatively,multiple elements. The laser wavelength may be chosen such that aportion of the laser energy is absorbed by the substrate surface. Thepower required is influenced by the absorption efficiency of thesubstrate surface. 10 watts or less of power may be suitable for mostoperations; however, more power may be used. Increasing the powerfacilitates marking at higher speeds.

XY motion of pickup head 200 may be coordinated with ON/OFF beammodulation to draw symbols (e.g., alphabetic, numeric and/or barcodetypes). The laser energy could be linearly modulated or pulse widthmodulated proportionally to marking speed, however simple full ON orfull OFF may be suitable.

The laser energy absorbed by substrate 258 may be used to vaporize orscar a PCB solder mask coating, PCB ink stencil markings, or apply alabel to identify the board by marking thereon, e.g., the board type,revision, serial number, manufacturing date, machine operators name,and/or production lot. Barcode marking may be applied for subsequentreading by other machinery or hand held barcode readers.

Symbols could also be drawn by laser motion along one axis and boardmotion along the other axis by means of a board conveyor or by thenormal use of the board motion axis where the pick and place machinemoves the board along one axis and the head moves along the other axis.Alternatively, the pick and place machine may move the board in two axisdirections and the laser could remain stationary.

Laser 900 could be mounted outside of pickup head 200. Additionally, thelaser may be mounted on its own separate single or dual axis motionplatform independent of the pickup head motion. The laser beam could bescanned with a rotating or oscillating mirror (e.g., galvanometer drivenmirrors) to mark a board that is stationary or moving.

2.0 Operation

Operation of the example pick-and-place machine 1000 will now bedescribed.

After the desired feeder cartridges 350 have been installed inpick-and-place machine 1000, pickup head 200 is moved to a positionadjacent a feeder cartridge 350 having a component to be picked. Sensors218 then scan the calibration marks on the feeder gear of the selectedfeeder cartridge. This position information is used to locate the feedergear so that rack gear 216 can be aligned and engaged with the feedergear. Such position information may also be used to determine a positionof the component pockets on tape 340 if the calibration marks on thefeeder gear are arranged to match the component spacing on tape 340.Next, gear driving mechanism 210 is lowered to cause rack gear 216 toengage feeder gear 355. Taking into account the position information ofthe feeder gear 355, motion system 400 then moves pickup head 200 aprecise distance such that rack gear 216 drives feeder gear 355 to index(i.e., incrementally move) tape 340, thereby causing the next componentpocket 343 to enter pickup zone 342.

After rack gear 216 is disengaged from feeder gear 355, the sensors 218again detect the position of feeder gear 350 by sensing the calibrationmarks on the feeder gear. This position information is used to preciselylocate the rotary orientation of the feeder gear and the componentpocket locations for storage by CPU 110 and later use in subsequent“pickups.” Scanning calibration marks after the feed move substantiallyeliminates the negative effects of backlash. That is, if there is adiscrepancy in actual distance moved and the intended distance ofmovement, such discrepancy can be corrected by a correction move in theY direction. Gear driving mechanism 210 is then returned to its raisedposition (shown in FIG. 11).

Next, the vacuum source is turned on and vacuum nozzle 230 is loweredinto pickup zone 342 to contact or nearly contact a component positionedin a component pocket 343 in tape 340. Due to the vacuum force, thecomponent is drawn up against distal nozzle opening 230(3).

The component is then imaged by component camera 251 and theabove-described squaring method is performed to obtain and effect both alinear XY correction and an angular correction of the component heldagainst the distal nozzle opening.

The vacuum nozzle is then positioned over the desired placement location(with both linear and angular corrections included) and lowered to placethe component (e.g., by pushing the component into solder paste) on thesubstrate 258. The vacuum source is then turned off and vacuum nozzle230 is raised leaving the component in place on the substrate. Thepickup head is then moved to the feeder cartridge having the nextcomponent to be picked and placed. This process is repeated until allthe desired components have been placed on the substrate. CPU 110 maystore computer program code structures to carry out the example methodof operation described above.

2.1 Control Computer Program Code Structures

The control program code structures 112, when executed by CPU 110,provide a system designed to simplify machine operation for the user.CPU 110 executes stored program code to provide advantageous set-upfeatures.

2.11 Auto-Setup

An example automated set-up process will be described. Feeder managementis often the largest part of the set-up process and an area where errorsare frequently made. The disclosed exemplary auto set-up systemsignificantly reduces set up time associated with assembling a newprinted circuit board and eliminates many error-prone processes.

A user may install feeder cartridges 350 at any feeder module locationin pick-and-place machine 1000. The feeder cartridges may be installedin full or half slots and may be placed in the machine without concernof the particular component (part) associated with a given feedercartridge. Each feeder cartridge has a permanent alignment target mark(e.g., on upper attachment portion 352(1)) that when measured bymulti-purpose camera 252 reports an exact location of the feedercartridge. Further, each feeder slot may include an optical sensor toconfirm proper installation of feeder cartridge 350 in pick-and-placemachine 1000.

Multi-purpose camera 252 in conjunction with optical interrupter 313will detect each feeder cartridge and determine the location of eachfeeder cartridge by its position (location information) inpick-and-place machine 1000. The multi-purpose camera 252 may also scana machine readable barcode on label 361 which will inform CPU 110 of theparticular component (e.g., identification information such as partnumber) associated with that feeder cartridge. As described earlier, theoperator also may simply read the alphanumeric text on label 361 toensure that the component identifying information (e.g., part number) onthe label matches the component identifying information (e.g., partnumber) on reel 330 containing the tape being fed through the feedercartridge, as a confirmation.

The system will then provide gathered feeder cartridge information to anassembly program which will identify any missing components. Should anycomponents be missing, the user can simply add the missing feedercartridges. The system will organize (e.g., schedule the picking andplacing of each component) the assembly of the substrate in accordancewith the location of each feeder cartridge and the identificationinformation of the components. The system may also offer optimizationsuggestions (e.g., to reduce assembly time).

In order to recognize and identify any missing components, the systemmay compare the gathered feeder information against pre-defined PCBinformation The pre-defined PCB information may include a listing ofeach required component and coordinates for the placement locations ofthe components for a given PCB assembly. This information may beprovided to CPU 110 to guide the assembly process. A comparison of thegathered feeder information and the pre-defined PCB may be displayed toan operator in the manner shown in FIG. 46. Missing components may behighlighted to prompt the operator to add the missing feeder cartridges.

The system will also automatically select and install vacuum nozzles asneeded. The vacuum nozzles 230 have machine readable identificationinformation (e.g., a barcode) provided on an outer surface of thenozzles. Multi-purpose camera 252 is configured to read identificationinformation on the vacuum nozzles and then automatically select thecurrently desired nozzle (e.g., from the nozzle changer cartridge 270)and install that nozzle on nozzle holder 231.

Additionally, the system provides flexible support for partial boardpopulation and various circuit board configurations. That is, forexample, the user may activate or deactivate placement of a singlecomponent, multiple components or all components of a given part number.

Panel arrays are easy to setup and may be built in a variety of ways. Itis often more efficient to build boards several at a time. The boardsmay be arranged in linear or rectilinear arrays. The user need onlyspecify the spacing of the boards in the array and the system willperform the remaining set-up procedures. In a first example, the systemmay build complete boards one at a time. An advantage of this method isthat the user may observe and inspect a complete board before buildingthe other boards. This affords an opportunity to correct errors beforebuilding the other boards. In another example, the system may place eachcomponent of a given type and designation on all boards in the arraybefore proceeding to the next component. This method is potentiallyfaster because it may reduce the frequency of nozzle changes.

2.12 Virtual Build

As part of an initial set-up procedure, the system may provide a virtualbuild feature that enables a user to confirm component alignment in thefeeder cartridges without wasting any components. A scanned image of theboard (substrate) to be assembled, having no components yet placedthereon, as shown in FIG. 38-1, may be uploaded to the system. Thescanned image is preferably a high resolution image. The image may beused to teach coordinate locations; however, CAD centroid data ispreferred for this function. The centroid data may include the componenttype/part number for all components, the x/y coordinate location on theboard for each component, as well as the orientation of each componenton the board.

The system may use individual stored images (C1 to C8) of the actualcomponents in each feeder cartridge, as shown in FIG. 38-2. As shown inFIG. 39, the system may overlay component images C1 to C8 onto thescanned board image in accordance with predetermined locations (e.g., ascontained in the centroid data) for placing each component (therebybuilding a virtual PCB).

In contrast to systems that create an image of the assembled board fromimported data, the instant system does not presume a componentorientation based on a user input (which if such input is incorrectresults in a placement error). By using a captured image (includingorientation) of the component on the tape, the possibility of usererrors may be greatly reduced or even eliminated. In some machines, itis difficult to even see the component in the feeder. Further,determining an orientation of the component in such a machine may befurther complicated by location (front, back, sides) of the feeder inthe machine.

The virtual build process eliminates errors that have been common place.The results of the virtual build process may be presented to the user ina number of arrangements. In one example, a realistic view of thefinished board is provided, as shown in FIG. 39. In another example, thesystem displays the components in a part number/feeder number organizedmosaic with rotation correction. Thus, for example, if three capacitorswere used from feeder cartridge number “17,” then three images would belinked to feeder cartridge “17” for viewing. Unlike the realistic mode,the mosaic mode would undo the component rotation so all components of aparticular type should appear the same. The user can simply focus onidentifying differences in the images of components of the same type(part number).

This system also logically facilitates the user in identifying the causeof errors. For example, if there is a problem with only a singlecomponent, the user may logically suspect that there is a problem withthe CAD centroid data. If there is a problem with all of the componentsfor a given feeder, then the user may logically suspect that the feedercartridge data (e.g., part number, part value (e.g., 0.01 uF/20V),package number, feeder orientation, tape width/pitch,polar/non-polar(n/p)) is the likely cause. If rotation of the componentsappears to be correct at 0° and 180°, but wrong at all other angles,then the user may logically suspect that the rotation direction in thecentroid data is backwards. If the location of some components is vastlywrong while the location of other components appears to be correct, thenthe user may logically suspect that the centroid data is incorrect.Further, if most or all of the component locations are off target by aconsiderable degree, the user may logically suspect that confusion inthe unit of dimensions (e.g., inch/metric) is the cause. An advantage ofthe system is that these “diagnoses” are much more evident as comparedto other systems.

Accordingly, a user may confirm placement of the various componentsagainst the pre-defined PCB data (described earlier). Unlike othersystems, no components are consumed in this virtual process ofconfirming feeder cartridge installation and alignment. Feeder cartridgealignment may pertain to whether the cartridge in mounted in the frontor back of the machine. Additionally, as described above, the virtualbuild process may also catch other errors such as erroneous CAD data anderrors with incoming translations (e.g., unit of dimension, rotationdirection, etc.). A user may correct an incoming translation error byapplying a revised rule to the entire board to be assembled.

Additionally, the pre-defined PCB data may be represented graphically,as shown in FIG. 40. Placement locations P1 to P8 for respectivelyreceiving components C1 to C8 may be disposed in accordance with thecoordinate information of the pre-defined PCB data. In this manner, thegraphical representation of the pre-defined PCB may be overlaid onto thevirtual PCB (e.g., with the overlaid image being partially transparentto facilitate visual comparisons) to provide a more intuitiveconfirmation procedure, as shown in FIG. 41. The user need only confirmproper placement of the component images C1 to C8 onto correspondingplacement locations P1 to P8. In an example shown in FIGS. 42 and 43,mistakenly installed feeder cartridges and/or feeder modules, improperlyplaced tape reels 330, etc., have resulted in misplaced components(e.g., C4 and C8) that may be easily recognized by the operator.

The system may also store the length, width and thickness of eachcomponent to later qualify each measured component as actually placed.This information may be used to test, adjust and perfect the videocentering process. For instance, when a component is measured (duringthe linear/rotational error correction process), the component must meetdimensional specifications to prevent attempted placement of an out ofposition or missing component. Components identified as a “mis-pick”will be rejected and a full image of the component will be stored fortroubleshooting.

2.13 Product Inspection

To facilitate finished product inspection, multi-purpose camera 252 maycapture images of each component as it is actually placed on substrate258. These images may be acquired after each placement or acquiredsequentially after the entire assembly is complete. Acquiring an imageafter each placement requires less pickup head motion and is faster;however, if a subsequent placement interferes with a previous placement,the image of the previous placement would not show the subsequentmovement of the component. So, capturing all of the images on acompleted assembly is the most error free process, but is also more timeconsuming. However, the inspection phase causes pickup head motion onlybetween nearby components, so the process is reasonably fast.

The system then organizes the images for easy inspection. For example,the images are rotated to the same orientation and then grouped (e.g.,by part number). An example of such display screen is shown in FIG. 45.The images are displayed in a mosaic array organized by component typefeeder cartridge. Each line of the array may display components of aparticular part number (i.e., component type) so that all of the imageson a line should look the same. By this method, even the slightestdissimilarity is easily noticeable to the user. For instance, byanalyzing a line of the array, an operator may readily detect whether infact the components installed on the substrate (a) are the samecomponent type; (b) are the intended component; and/or (c) wereinstalled with the correct orientation.

As shown in FIG. 45, a component of a different type mistakenlyinstalled in a “component-type 1” location may be easily identified asdissimilar to the other components. Additionally, a misalignedcomponent-type 2 component may be identified by an operator due to itsdifferent orientation from the other components. Further, once thesubstrate solder is reflowed, the same process may be used to inspectthe finished substrate.

As another finished product inspection procedure, the graphicalrepresentation of the pre-defined PCB (described earlier) may beoverlaid onto an image of the actual finished PCB (e.g., captured bymulti-purpose camera 252), as shown in FIG. 44, to ensure correctplacement of the components.

One skilled in the art will recognize that for each of the overlayprocedures described above, either image may serve as the overlaidimage. Further, those skilled in the art will also recognize thatproviding one or both images in at least partial transparency mayfacilitate comparison.

3.0 Multi-Component Vacuum Nozzle

Instead of the previously described vacuum nozzle 231, a multi-componentvacuum nozzle system 500, shown in FIGS. 21-35, may be used inpick-and-place machine 1000. The multi-component vacuum nozzle systemincludes vacuum nozzle 502 attached to body portion 506. Collar 502(1)of the nozzle abuts the body portion. Vacuum nozzle 502 is configured tosimultaneously carry multiple components. In this manner, multiplecomponents may be delivered to the substrate during each trip of vacuumnozzle 502 from feeder cartridges 350 to the substrate.

Vacuum nozzle 502 is configured such that components enter the nozzlethrough distal nozzle opening 504. Vacuum nozzle 502 has a plurality ofinner walls 507 forming a hollow portion 503, as best shown in FIG. 35(only two of four are shown). The components may be stacked one on topof another in hollow portion 503. By this arrangement, the componentsare automatically aligned by the inner walls 507 of vacuum nozzle 502,thus there is no requirement for a component camera to correctmisalignments of the components. However, vacuum nozzle 502 may still berotated to place components at any angle. The inner walls 507 of vacuumnozzle 502 are designed to match the shape of the components, therebyautomatically aligning the components. In the illustrated example, thecomponents are rectangular. By way of example, if the components are0.05×0.08 inches, a suitable distal nozzle opening 504 may be0.052×0.082 inches. Hollow portion 503 may have the same cross-sectionaldimensions as the distal nozzle opening. Hollow portion 503 is made longenough to accommodate several components. A chamfer 505 may be providedat the distal nozzle opening 504 to assist component entry.

Stop 512 is slidably received in hollow portion 503. Four air passages504(1), 504(2), 504(3), 504(4) are formed along respective corners ofthe hollow portion 503 to allow vacuum suction to pass around stop 512,as best shown in FIG. 30. It should be noted that more or fewer airpassages may be provided. Further, the location of the air passagesaround stop 512 may vary. For instance, instead of being positioned atthe corners of the stop, the air passages may be formed between thecorners. One skilled in the art will further recognize that the shape ofthe hollow portion may vary in accordance with the shape of thecomponent to be picked and placed; thus the air passages may bepositioned in any suitable location in the hollow portion.

In operation, the vacuum force draws a component into hollow portion 503via the distal nozzle opening 504 so as to abut against stop 512. Thestop 512 prevents the component from flipping. Once the component isestablished in place against the stop and between the inner walls 507,the stop is retracted into hollow portion 503 by a distance equal to thethickness of one component to make room for the next component. Byproviding a space at the end of hollow portion 503 that is only largeenough for a single component, motion of the component is fullycontrolled. This process may be repeated to stack as many components asdesired (e.g., up to 10 or more, 2-5, 5-10, 10-20, 15-20, up to 20, 20or more) into hollow portion 503.

The stop 512 may later be moved toward distal nozzle opening 504 to pushthe components into the solder paste on the substrate. Stop 512 ispreferably controlled by a servo step motor or a voice coil actuatorwith position feedback to enable precise incremental movements. Pickuphead 200 may also incorporate a conventional force feedback measurementsystem to help guide the placement process.

3.1 Confirmation of Component Pickup

An optical sensor (e.g., LED/phototransistor sensor) 516 may be providedat an end portion of vacuum nozzle 502 to detect when a component hasbeen successfully picked up. Sensor 516 is configured to emit a lightbeam from one side of the nozzle and to detect the light beam at theother side of the nozzle. When a component is successfully picked up,the component will block the light beam, thereby indicating a successfulpickup. However, those skilled in the art will recognize that the sensorcould depend on light reflection rather than light blockage in whichcase the sensor and emitter would be positioned on the same side of thenozzle. Additionally, mirrors, optical fibers, prisms, reflectors and/orlight pipes may be used to transport light to/from stationarysensors/emitters on pickup head 200, thereby eliminating the need forinductive power transfer to sensors/emitters on vacuum nozzle 502.Further, other non-optical sensing methods may be employed. Forinstance, magnetic sensors that utilize induction or eddy current couldbe used, as well as other techniques such as ultrasonic detection,fluidic cross flow, air pressure or capacitance change. Cavity resonatefrequency would change with component presence which could be detectedin both acoustic and electromagnetic spectrums.

Further, as one skilled in the art will understand, an LED may be usedboth to emit light and to serve as a photodiode to sense light. Suchdual function arrangement may reduce the space required by sensor 516since an LED is typically smaller than a light-sensing photodiode orphototransistor.

An inductive coupling system is provided in the exemplary embodiment toprovide power to illuminate the LED and to return an optical statussignal over the inductive link. The inductive coupling system includestwo coils that inductively couple without touching. Referring to FIGS.31-34, primary coupling coil 530 is arranged to be fixed on pickup head200 while secondary coupling coil 510 is mounted on vacuum nozzle system500. Secondary coupling coil 510 may be mounted on seat 508 of bodyportion 506 and connected to sensor 516 via a flexible printed circuitboard 520. A suitable air gap (e.g., 0.25 inches) may exist betweenprimary coupling coil 530 and secondary coupling coil 510. This enablesvacuum nozzle 502 and sensor 516 to be easily dismounted forreplacement. Further, rotation of the vacuum nozzle by nozzle rotationmotor 234 is not complicated by electrical connection since primarycoupling coil 530 is fixed on the Z axis and secondary coupling coil 510is mounted on the vacuum nozzle system. A flange 509 may be arranged onan upper side of seat 508 to contain secondary coupling coil 510. Seat508 and flange 509 are electrically non-conductive, as one skilled inthe art will understand.

An example of a circuit for the inductive coupling system is shown inFIG. 36. Primary coupling coil 530 and associated circuits are includedon pickup head 200. Secondary coupling coil 510 and associated circuits(included on flexible PCB 520) are mounted on vacuum nozzle system 500.Primary coupling coil 530 is driven with a high frequency AC signal(e.g., 3.0-6.0 MHz). The signal could be a square wave, pulse train,filtered square wave or sinusoid which would radiate the least radiointerference. A resistor (R1) acts as a current sensing shunt allowingprimary drive current to be measured. A clamp diode (left half of D1)may parallel the shunt resistor (R1) to reduce its impedance during anLED drive phase. When output of secondary coupling coil 510 is in anegative half phase, a diode (top half of D2) and a capacitor (C2)provide DC to power the LED and create an illuminative output. Thecapacitor (C2) stores energy so that the LED light output will persistacross the other (positive) half phase.

The positive half phase powers the light sensing system. Either aphototransistor or an LED (PHOTO1) operating in photo sensing modeprovides a signal that is amplified by a suitable transistor (Q1). Thistransistor draws more current when the sensor is illuminated and verylittle when the sensor is not illuminated. The magnitude of the currentdraw during the positive half phase reports the light/dark status of alight sensor. The shunt resistor (R1) in series with primary couplingcoil 530 reports the LED drive current as a negative signal and thephoto current as a positive one. A simple diode (right half of D1)separates the photocurrent from the LED current for easy measurement.Ultimately, the signal is conveyed as an analog level to a processorchip (e.g., CPU 110). The processor may note a light level just prior tobeam blockage to reduce the effects of variation and drift. Theprocessor may then set a threshold based on this value to reliablyrecognize small changes.

In another example, vacuum nozzle 502 may include a planar secondarycoupling coil 522 (e.g., a planar spiral coil connected to or as part offlexible PCB 520) instead of the wire coil 510 for inductively couplingwith primary coupling coil 530, as shown in FIG. 35. The planarsecondary coupling coil 522 is integrally connected and easier toassemble while the wire secondary coupling coil 510 is closer to primarycoupling coil 530 and thus has greater coupling efficiency. The planarsecondary coupling coil 522 may be disposed on either a distal side offlange 506(1) as shown in FIG. 35 or a proximal side of flange 506(1) asshown in FIGS. 31-34. Further, one skilled in the art will understandthat either secondary coupling coil 510 or planar secondary couplingcoil 522 would be used at any given time; however, both coils may bedisposed on the nozzle system.

In another example, a vacuum sensor (not shown), instead of the opticalsensor 516, could be provided near an end portion of vacuum nozzle 502to confirm a successful pickup by detecting a change in pressure when acomponent occludes the hollow portion 503 thereby restricting vacuumflow.

3.2 Actuation of the Stop

A voice coil actuator may be employed to create a force to move stop 512along hollow portion 503. A rare earth magnet 514 (e.g., 0.236 inches indiameter and 0.236 inches long) is attached to a magnet-receivingportion 513 at an upper portion of stop 512, as shown in FIG. 22. Thestop is nonmagnetic to prevent flux from conveying down to thecomponents (which are typically magnetic). Stop 512 and magnet-receivingportion 513 are slidably received in the body portion 506. Referring toFIGS. 31 and 32, a linear drive coil 540 may be configured to be fixedon pickup head 200 for inductively coupling with magnet 514 to move stop512.

The space between linear drive coil 540 and magnet 514 may be as smallas possible to optimize magnetic coupling. Linear drive coil 540controls the position of the magnet 514 and the stop 512 with a magneticfield created by current flow in the linear drive coil, as one skilledin the art will understand. A suitable material for body portion 506 iscarbon fiber. Current in linear drive coil 540 is preferably controlledby a class-D-amplifier with pulse width modulation.

Actuation of magnet 514 and stop 512 is preferably servo controlled toenable precise movements. The position of the magnet may be accuratelydetermined with a magnetic field strength sensor. This technique isdescribed in Honeywell application note AN211, which is incorporatedherein by reference. The position may be reported magnetically as ananalog voltage. This may be used in a proportional-integral-derivative(PID) servo loop to control the current in linear drive coil 540.Current in linear drive coil 540 may be adjusted as necessary to keepstop 512 in a desired position. Because the static magnetic field frommagnet 514 and the dynamic field from linear drive coil 540 may bothinfluence the magnetic field strength position sensor, positionmeasurement requires measuring the static component from magnet 514without outside influence. In order to achieve this, current in lineardrive coil 540 may be turned off briefly during position measurementintervals. Several thousand measurements per second may be taken, as oneskilled in the art will understand.

The combination of the voice coil actuator and the magnetic positionfeedback sensor provides very high resolution force measurement. Becausethe voice coil produces a force in proportion to drive currentindependent of magnet position over a modest range, the voice coil actslike a nearly linear spring. Thus, the voice coil actuator combined withthe position sensor is somewhat analogous to a spring scale withmilligram resolution. The system is adept at measuring force vs.distance relationships, since force is easily controlled as a directfunction of current and distance is measured directly with the magneticsensor. For relatively small parts, precision force control is essentialto placing the parts without damage. It is noted that other feedbacksystems may also be used.

Vibration of stop 512 may be induced to aid in picking up and aligningcomponents in the hollow portion 503. This vibration may be introducedas hysteresis in the servo loop to produce vibration at the update rate,or the vibration could be introduced as a separate error signal in theloop to obtain vibration at a lower frequency. The vibration may beturned on or off and the frequency and amplitude of the vibration may bechanged to accommodate various components.

Additionally, optical sensor 516 may be used to confirm the location ofthe components held within hollow portion 503. The position of thecomponents may be relative to a reference location such as the bottom ofthe last component picked up by vacuum nozzle 502. Thus, all movementsof stop 512 may be relative to this reference location. This arrangementmay diminish the need for accurate linearity over long travel distancesof the magnet. This arrangement also mitigates variation in fieldstrength of different magnets on different vacuum nozzles.

In an alternative arrangement, movement of stop 512 may be accomplishedby a motor driven screw connected to the stop, as should now beappreciated by those in the art. A connection between stop 512 and theservo system is accomplished with a toroidal ring magnet on the outsideof the body portion 506 that couples and captures a cylindrical magnetattached to the stop on the inside of the body portion. The stop isnonmagnetic to prevent flux from conveying down to the components. Arare earth magnet is used. The ring magnet and the cylinder magnet aremagnetized along their lengths or thicknesses. These magnets areoriented so their opposing poles align and attract. While this couplingis compliant, it takes a large force to displace the magnet whencaptured inside the toroid. The magnetic coupling is essentially solidin the vertical displacement axis but allows friction-free rotation. Thetoroidal magnet is driven by a lead screw which is in turn driven by agear and a long pinion. A servo or stepper motor may be used to controlrotation of the lead screw and thus the vertical position of stop 512.

3.3 Operation

In operation of the example multi-component vacuum nozzle system 500, acalibration process is performed to set the position of stop 512 beforea first component is picked from tape 340. Stop 512 is first lowered tobreak the light beam from sensor 516 and is then raised until the lightbeam is restored. This position of stop 512 may be a sufficient startingposition for picking thin components; however, for thicker components,the stop may be raised further. Next, the vacuum source is turned on andvacuum nozzle 502 is lowered to nearly contact tape 340 between adjacentcomponent pockets 343. Then, the vacuum nozzle is moved over a componentpocket 343 to draw the component into the vacuum nozzle. A successfulpick-up of the component is reported by sensor 516. Instead of sensor516, it is noted that the previously described vacuum sensor may beused. Stop 512 is then moved up a distance equal to the thickness of acomponent in order to make room for the next component. Sensor 516 thenreports that there is no blockage of the light beam. The vacuum nozzleis moved over the next component pocket 343 to pick the next component.This process may be repeated as necessary to pick a desired number ofcomponents. The tape may be indexed to bring the components to thevacuum nozzle 502 one at a time, or possibly, a large number ofcomponent pockets 343 may be simultaneously exposed in an elongatedpickup zone so that the vacuum nozzle 502 can move across an exposedsection of tape to rapidly pick up components. That is, each feed movemay expose multiple components (e.g., 2-7, 7 or more, 10, 10 or more,15-20, 5-15, 15 or more, 20, 20 or more).

If a component is unable to be picked by vacuum nozzle 502, the nozzlemay re-try the pickup or go on to a subsequent component instead.Further, if the component ultimately is unable to be picked up by vacuumnozzle 502, the CPU 110 may keep track of such component and adjust theplacement process accordingly so the nozzle does not attempt to placethe (“missed”) component.

As described earlier, vibration of stop 512 may be induced to aid inpicking up components. The stop may be lowered to a position near distalnozzle opening 504 and then a slight vertical vibration of stop 512 maybe induced. The component would remain in motion after being drawn intohollow portion 503 due to the vibration of stop 512. However, in anotherexample, the vibration may be stopped once the component is picked up.The stop is then moved up to confirm the component pickup and to makeroom for the next component. The vibration helps components find theirway into and past distal nozzle opening 504, which for example may be achamfered opening.

Once a desired number of components are loaded into hollow portion 503of vacuum nozzle 502, the placement process may begin. The vacuum nozzlewill be positioned over the first placement location and lowered tonearly touch substrate 258. Stop 512 is then lowered to push (or eject)a component out of nozzle opening 504 and into solder paste on thesubstrate. Once the component has been completely removed from vacuumnozzle 502, the vacuum force will be smaller than the adhesive force ofthe solder paste thereby causing the component to remain on thesubstrate as the vacuum nozzle 502 is raised. Because of the highbandwidth of motion of stop 512, components may be rapidly placed whilepickup head 200 is still moving. Since slowing the pickup head to acomplete stop consumes a great deal of time, keeping the pickup headmoving at even a modest pace adds significantly to performance.

The stop positioning system can also report push force and distance withfine resolution, as described previously. Referring to FIG. 47, theshape characteristics of the force vs. distance curve can be used toidentify the presence or absence of solder paste. Placing a component ona board without paste will report an abrupt rise in force because thecomponent will experience no resistance until it hits the hard board. Onthe other hand, placing a component in paste will report a more gradualrise in force as the displacement of the paste cushions the impact.Without solder paste, the component will not connect to the board whichwill cause a defective assembly. Detection of absent solder paste issignificant in preventing defective assemblies. A force vs. distanceprofile of stop 512 may be analyzed and compared (e.g., with a controlprocessor) to a predetermined force vs. distance profile to determinethe presence or absence of solder paste.

Additionally, sensor 516 may be used to confirm that a component wasactually placed in the paste on the substrate. Stop 512 and the stack ofcomponents may be raised to confirm placement of a component byverifying that the light beam is not blocked. A component that will notremain on substrate 258 (e.g., because of missing paste) may be purgedby placing the component in a dump area having an adhesive coated tapewhich retains the component.

While the examples discussed above have been described in connectionwith what are presently considered to be practical and preferredfeatures, it is to be understood that appended claims are intended tocover modifications and equivalent arrangements included within thespirit and scope of these examples.

What is claimed is:
 1. A nozzle system for picking up and placing components on a substrate, said nozzle system comprising: a nozzle having an elongated hollow portion; and a stop slidably and adjustably disposed within the hollow portion and configured to define an operative internal length of said hollow portion, wherein the hollow portion is configured to accommodate a plurality of components successively drawn therein along its internal length and successively ejected therefrom as said stop is adjusted to accommodate different numbers of components within said hollow portion.
 2. The nozzle system according to claim 1, wherein the nozzle has a plurality of inner walls at least partially defining the hollow portion, and a distal nozzle opening is formed in the nozzle and configured such that the plurality of components enter the hollow portion through the distal nozzle opening.
 3. The nozzle system according to claim 2, further comprising a vacuum source passage in fluid communication with the hollow portion, wherein the nozzle includes a plurality of air passages formed in the inner walls to provide fluid communication between the vacuum source passage and the distal nozzle opening.
 4. The nozzle system according to claim 1, wherein the nozzle includes a sensor disposed adjacent the distal nozzle opening to detect the presence of a component in the hollow portion.
 5. The nozzle system according to claim 4, wherein the sensor is an optical sensor including a light emitting portion and a light detecting portion.
 6. The nozzle system according to claim 4, further comprising an inductive coupling system to provide electrical power to the sensor.
 7. The nozzle system according to claim 6, wherein the inductive coupling system includes a transformer secondary coil to provide electrical power to the sensor.
 8. The nozzle system according to claim 7, further comprising a flexible printed circuit board connecting the transformer secondary coil and the sensor.
 9. The nozzle system according to claim 8, wherein the transformer secondary coil is a planar coil.
 10. The nozzle system according to claim 4, wherein the sensor is a vacuum sensor configured to detect a change in pressure caused by occlusion of the hollow portion when a component is contained therein.
 11. The nozzle system according to claim 2, wherein the nozzle includes at least one of a) mirrors; b) optical fibers; c) prisms; d) reflectors; and e) light pipes disposed on the nozzle to transmit light to/from the nozzle from an external location to detect the presence of a component in the hollow portion.
 12. The nozzle system according to claim 1, further comprising a magnet attached to the stop, the magnet being inductively coupled to a drive coil, wherein a position of the stop within the hollow portion is controlled by an electrical current in the drive coil.
 13. The vacuum-holding nozzle system according to claim 12, further comprising a magnetic position sensor to magnetically detect a position of the magnet, wherein position measurements are taken when no electrical current is supplied to the drive coil.
 14. The nozzle system according to claim 1, further comprising a screw connected to the stop, wherein rotation of the screw adjusts a position of the stop within the hollow portion. 